A blood pump, such as a percutaneous intracardiac blood pump assembly, is introduced in the heart to deliver blood from the heart into an artery, such as the pulmonary artery. When deployed in the heart, a blood pump assembly pulls blood from the left ventricle of the heart and expels blood into the aorta, or pulls blood from the right ventricle and expels blood into the pulmonary artery, through a cannula. Blood pump assemblies are introduced surgically or percutaneously during a cardiac procedure through the vascular system. In one common approach, pump assemblies are inserted by a catheterization procedure through the femoral artery using a guidewire.
An introducer is inserted into the femoral artery through an arteriotomy to create an insertion path. A placement guidewire is then advanced distal end first through the sheath into the artery. Once the guidewire has been inserted into the artery, the pump assembly, including a pump and a cannula, is backloaded onto the proximal end of the guidewire and pushed along the guidewire and into the patient. The pump assembly may then be used in conjunction with a catheter.
As defined herein, backloading involves inserting the proximal end of the guidewire, which remains outside the patient, into the distal end of the catheter and then advancing the catheter distally over the wire Backloading the pump assembly allows the guidewire to remain in position within the patient while different size catheters or sheaths are inserted and removed during the course of a procedure. But the cannula of the pump assembly can have a tortuous shape, or the cannula can be stiff. In these cases, the guidewire may not be stiff enough to allow backloading of the pump through to the pulmonary valve, and as a result the cannula of the pump may displace the guidewire out of the pulmonary valve. For example, for systems delivering blood from the inferior vena cava to an opening in the pulmonary artery, the cannula of the pump may be a 3D shape with two “S” turns in different planes. This can make backloading and insertion of the pump assembly into a patient particularly difficult.